walter



( No Model.) Q 2.Sheets-Sheet 1. H. E. WALTER & G. BATGHELOR.

DYNAMO ELECTRIC MACHINE.

No. 360,258. Patented Mar. 29, 1887.

(No Model.) 2 Sheets-Sheet 2. H. E. WALTER & O. ,BATOH ELOR.

DYNAMO ELECTRIC MACHINE.

No. 360,258. Patented'Mar. 29. 1887.

- Machines, of which the following is a specifi a direction the same as UNITED STATES PATENT OFFICE.

HENRY E. WALTER, or CLIFTON, ND CHARLES nArcnELoa, on NEW YORK, N. Y.

DYNAMO-ELECTRIC MACHINE.

SPECIFICATION forming part of Letters Patent No. 360,258, dated March 29, 1887.

"Application filed November G, 1886. Serial No. 218110. (No model.)

To all whom it may concern.-'

Be it known that we, HENRY E. WALTER, of Clifton, in the county of Richmond and State of New York, and OHAELEs BA'roHELoR, of New York city, in the county and State of NewYork, have j ointlyinventeda certain new and useful Improvement in Dynamo-Electric cat-ion.

The object of our invention is to provide a dynamo-electric machine in which the nonsparking points of the armature will remain constant, and the position of the brushes'will never have to be adjusted for changes of load or armaturecurrent.

Heretofore attempts have been made to ac complish this by providing means for cons'tantly neutralizing the magnetism of the armature. We have found that another cause of spark and variation of non-sparking points is the self-induction of the armature-coils which occurs as each coil leaves the commutator-brushes, and which varies with every change in load and armature-current.

Our invention consists, mainly, in certain means for neutralizing this self-induction by producing in each coil at the instant when it leaves the brushes a certain electro-motive force. The means which we employ for this purpose in one form of our invention or one way of using it, prevents change of non-sparking points without decreasing the effect due to the armature magnetism-that is, by neutral izing the self-induction only. In the preferred form, however, it acts also to neutralize the effect of the magnetism of the armature as well as to neutralize the self-induction. The latter arrangement is preferred, because it adds to the efliciency of the machine, while the former detracts from it, as will be hereinafter more fully explained.

The means which we employ is a stationary coil surrounding the armature supported upon the pole-pieces of the field-magnet connected in series with the armature-coils, and so situated that a magnetic circuit produced by it intersects the armature-coils at the normal neutral line, or neutral line at no load,and in that of the lines of force from the pole-piece which the coil is approaching. This is the point at which the commutator-brushes are placed or to which they are connected. Thus an electro-motive force is generated in the coils at this point,

which acts to neutralize their self-induction,

and which varies with every variation of the armature-current,so that the neutralization is constant and the non-sparking points remain always the same.

The above may be more clearly understood by reference to the annexed drawings, in which Figure I is aview in elevation of an Edison dynamoelectric machine embodying our invention in its preferred form. Figs. 2 and 3 are diagrammatic views showing the main feature of ourinvention in the preferred form. Fig. 4 illustrates another form of the invention, and Figs. 5 and 6 show different ways of employing our invention in connection with a field-magnet of the Siemens form.

A is the dynamo electric machine or elec tro-dynamic motor.

Referring mainly at present to Fig. 2, N S are the poles due to the field, and N S those due to the armature magnetization. The neutral line at no load is at a a, and it is to these points the commutator-brushes are connected. The lines of force from the field-magnet are represented by I) b. A coil, 0 c, is wound in grooves in diagonally opposite parts of the pole-pieces, said coil being preferably in the position as shown in Fig. 3, bounded by diametrical lines through the armature. This coil is connected in series with the generating-coils of the armature, as is shown in Fig. 1. Its ends are brought around the end of the armature in any suitable manner, as seen in Fig. 3. It may be held in position by metal strips or plates 1. The poles due to this coil in Fig. 2 are at N S and the mean poles of the armature at n s.

The line of the nonsparking points is never the same as the neutral line at no load; but the former is always a little in advance of the latter. This, as we have said, is due mainly to the self-induction of the armaturecoils, which ensues as each coil leaves the commit tator -brushes, and the position of the nonsparking points therefore changes with every coil 0 0, however, forms a local magnetic ciri'or large machines the increase of magnetizachange of. load and armature-current. It is for this reason that the commutator-brushes ordinarily have to be sooi'ten adjusted. The

cnit, Whose lines of force (represented by d d) intersect the coils at the neutral line or place where the brushes are connected, coming from the direction of the pole-piece which the generating-coils are approaching, and this neutralizes or destroys the self-induction and prevents spark; and the coil 0 0 being in series with the armature, its current varies with that in the armature-coils, so that the neutralization is constant and the non-sparking points remain always the same. The coil 0 c, placed as shown in Fig. 2, also acts to strengthen the field by producing two opposite poles at the side of the armature-poles, the resultant of which is n s, which is in such a position as to strengthen the total field. This action tends to compound the machine, since every increase of armature-current leads to an increased field strength. For small machines this alone may be used as a constant potential generator; but

tion will be too great, and we therefore add another feature, which also constitutes part of our invention. This consists of an extra differential field-magnet coil, B, wound over the main field-coils and connected in series with the armature, so that it partially neutralizes the'effect on thefield of the coilscc. By properly proportioning the coils the machine is made to maintain a constant potential. The same arrangement acts in the same way also in electrodynamic motors to maintain the non sparking points constant. Upon the reversal of the machine the current is of course also reversed incoil c, and the action remains the same. In this case the effect on the field will be to weaken instead of strengthen it; but the extra coil 13, being also reversed, keeps the field up to the proper point.

The arrangement in Fig. at is that which prevents variation of non-sparking points by neutralizingtheselfinductiomatthesametime magnetizing the armature in the opposite direction from the arrangement in Fig. 2. In this arrangement the coils c are placed on the sides of the armature opposite to those in the preferred form, though still in such position that their lines of force out their armature. coils at the normal neutral line and in the right direction. W'e have found that this also prevents the change of nonsparking points; but we prefer not to use it, especially in gencuit of the u erators, because, as will be seen, the lines of force from coil 0, in passing from the armature to the field-magnet, oppose the lines of force from the magnet, and therefore tend to weaken the field strength, which is of course undesirable. This is shown by the position of the mean poles, which is opposite to their posi tion in Fig. 2. In motors the reverse is the case, since the total field strength is increased instead of weakened. By placing the coils c c in the positions shown a good magnetic circuit is .provided "for it, only a small part of the cirpper part of the coil being through the air.

Figs. at, 5, and 6 show arrangements for a Siemens form of field-magnet. In Fig. 4- the coil 0 is wound in grooves diagonally opposite each other in the pole-pieces.

In Fig. 5 lips e e extend from the pole-pieces, which hold the coil in place,and also assist in forming a path for the local magnetic circuit.

We are aware of the patent to Thomson, No. 333,578, dated January 5, 1886, and we do not claim anything shown and described in that patent.

Vhat we claim is 1. The combination, with a dynamo-electric machine or electro-dynamic motor, of a sta tionary coil carried by the pole-pieces of the field-magnet in series with the armaturecoils and wound outside the same at diagonally-op posite points,and in such position that a magnetic circuit of said coil intersects the armature-coils at the normal neutral line, whereby the self-induction in the armature-coils is neutralized, substantially as set forth.

2. The combination, with a dynamo-electric machine or eleetro-dynamic motor, of a stationary coil inseries with the armature-coils and wound outside the same upon the poles of the field-magnet at diagonallybpposite points, and in such position that a magnetic circuit of said coil intersects the armature-coils at the normal neutral line, and an extra differential coil upon the field-magnet, also in series wit-h the armature, substantially as set forth.

3. The combination, in a dynamo-electric machine, with the coil 0, of the lips c on the field-magnet, substantially as set forth.

This specification signed and witnessed this 1st day of November, 1886.

HENRY E. W'ALTER. CHAS. BATGHELOR. lVitnesses:

WM. PEZER, E. O. ROWLAND.

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